Error: Invalid character

╷
│ Error: Invalid character
│
│   on main.tf line 15, in resource "aws_db_instance" "my_mariadb_instance":
│   15:   db_subnet_group_name =  ${module.vpc.database_subnet_group}
│
│ This character is not used within the language.
╵
Solution: make sure to use "${module.vpc.database_subnet_group}" between " "

See also

• terraform plan: [ -refresh-only | -lock=false | -target | -var-file | will be created | --help], Terraform plan errors, Terraform plan examples, Terraform plan execution errors, (known after apply)